Spring fork

ABSTRACT

A spring fork, in particular for bicycles, with a suspension system and a hydraulic damping system, wherein a compression stage damping system ( 6 ) is provided for a spring deflection process and a traction stage damping system ( 5 ) is provided for a rebound process. At least one piston ( 3, 16, 27 ) is provided, which is located in the cylinder ( 2 ), and at least one connecting passage ( 17, 17   a ) is provided which connects the cylinder chambers located on both sides of the piston and is intended for the overflow of hydraulic medium ( 21 ). The compression stage damping system ( 6 ) which is activated during the spring deflection process can be blocked by closing the connecting passage (lockout). At least with the compression stage damping system ( 6 ) blocked, if appropriate also with the traction stage damping system ( 5 ) also blocked, a bypass passage ( 11, 20, 20   a ) which has a reduced cross-section in comparison to the connecting passage ( 17, 17   a ) is opened. As a result, the strong damping effect is largely maintained, in particular during the rocking peddling action, but on the other hand, automatic return of the fork to its initial position (sag position) is made possible.

BACKGROUND

The invention relates to a spring fork, particularly for bicycles, witha spring and a hydraulic damping system, with a compression stagedamping system being provided for a spring deflection process and atraction stage damping system for a rebound process, having at least onepiston located in a cylinder and at least one connecting passageconnecting the cylinder spaces located on both sides of the piston,intended for the overflow of the hydraulic medium, with the compressionstage damping system, activated during the spring deflection process,can be blocked by closing the connecting channel. (lockout).

Such lockout-settings result in an extremely high damping and thereforeprevent the strong dipping of the frame and the rocking of the forkduring any rocking peddling action, which is particularly used in uphillpassages.

For this purpose, the compression stage damping system is blocked sothat practically no spring deflection is possible. However, this has theresult that the fork during ever so slight motions deflects increasinglyfarther, so that then particularly when riding uphill uncomfortable andalso ineffective riding positions and a worsened seating position aregiven.

SUMMARY

The object of the present invention is to create a spring fork of thetype mentioned at the outset, by which the above-mentioned disadvantagesare avoided, with particularly the disadvantages of a changed positionof the fork and/or the frame occurring during rocking peddling actionsis prevented.

In order to attain this object it is provided that at least one bypasschannel with a cross-section narrowed towards the connecting channel isopened in a blocked compression stage damping system.

The cross-section of the connecting channel or the throttling channel issized here such that the strong damping effect remains to a largeextent, and on the other hand, an automatic return of the fork into itsdefault position (sag position) is made possible. This return can occurwithin a few seconds, for example.

Here, it is particularly beneficial that no operation is necessary forthe reset actions, i.e. that it occur automatically.

According to a practical embodiment the connecting channel and thebypass channel are arranged in the piston and can alternating be openedand closed.

Another embodiment provides that a closing element is provided at aconnecting channel for a partial closing of the connecting channel to across-section equivalent to the bypass channel.

Depending on the embodiment of the spring fork and/or the damping systemany of the above-mentioned embodiments can optionally be used.

According to one embodiment of the invention, both the compression stagedamping system as well as the traction stage damping system can belockable, with at least one bypass channel being provided having areduced cross-section in reference to the connecting openings.

When the lock is engaged, compression and rebound of the fork are bothlargely blocked. However, due to the existing bypass channel the neutralposition (sag) can be automatically set to different basic stresslevels, for example. Even during uneven riding, the fork automaticallyadjusts to the sag level.

If this automatic adjustment is undesired, for example due to differentfundamental stress, a blocking valve may be provided serially inreference to a parallel switch comprising compression state dampingsystem and traction stage damping system according to another aspect ofthe invention to be patented independently.

In this case, the compression stage damping system and the tractionstage damping system are both completely blocked. In this embodiment,when the lock is disengaged any intermediate position of the fork can beadjusted by an appropriately different stress and then be fixed byengaging the lock. The fork is then locked to the respective position.

Another embodiment according to the invention provides that optionallyonly the compression stage damping system is blocked entirely or with abypass, or both the pressure stage damping system and the traction stagedamping system are blocked. In the latter case, both a blockage with abypass or a complete blockage can be provided.

When several different settings are provided with regard to the dampingadjustment, it is beneficial to provide a remote control for switchingthe spring fork to said different operating conditions.

This way, switching or adjustments to different terrain conditions canoccur during the ride, without stepping down.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional embodiments of the invention are listed in the furthersubclaims.

In the following the invention with its characteristic features isexplained in greater detail using the drawings.

Shown are:

FIG. 1 an operating diagram of a one-piston damping device with acompression stage damping system that can be blocked and a bypasschannel switched parallel for locking,

FIG. 2 an operating diagram having a one-piston damping device and acompression stage damping system that can be locked and a traction stagedamping system that can be locked and a bypass channel switched parallelto the lock,

FIG. 3 an operating diagram with a one-piston damping device and ablocking valve switched serial in reference to a parallel switchcomprising a compression stage damping system and a traction stagedamping system,

FIG. 4 a partial longitudinal cross-sectional view of a damping leg of aspring fork having a fixed pressure stage piston and a compression stagedamping system that can be blocked in an open position,

FIG. 5 a view equivalent to FIG. 4, however, here with the compressionstage piston being in a locked position,

FIG. 6 a longitudinal cross-sectional view of a lock-out piston in aperspective view and an open position, and

FIG. 7 a view similar to FIG. 6, however, here in a blocked position ofthe lockout piston.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIGS. 1 through 3, the damping arrangements 1 through 1 b are shown,which are provided with a one-piston damper having a piston 3 guided ina cylinder 2. The black arrows PF1 symbolize the motion and the oil flowduring the rebound process (traction stage), while the white arrows PF2symbolize the motion or the oil flow of the hydraulic oil 21 during thecompression process (compression stage.)

A hydraulic circuit 4 is connected to the cylinder 2, which in FIG. 1 isprovided with a traction stage damping system 5 and a lockout-device 7,arranged serially in reference to a compression stage damping system 6.The traction stage damping system 5 and the compression stage dampingsystem 6 each include a non-return valve 8 and a throttle 9, with thethrottle 9 of the traction stage damping system 5 being embodied in anadjustable fashion. The compression stage damping system 6 may also beadjustable, if necessary.

The lockout device 7 is arranged in line in reference to the compressionstage damping system 6, provided with a control valve 10 and a throttle12 as a bypass channel 11 of said path valve 10.

When the compression stage damping is locked by the valve 10, arrangedserially, i.e. the path valve 10 is closed, the bypass 11 remainsoperational via the throttle 12. This bypass is designed such thatalthough a very strong damping effect is given for the compressionstage, yet via the throttle 12 a return of the spring fork into theso-called sag-position is possible. Due to the fact that the tractionstage damping system is arranged parallel in reference to the serialarrangement comprising a traction stage damping system and thelockout-device 7, the function of the traction stage damping systemremains unaffected.

FIG. 2 shows a damping arrangement la, in which the traction stagedamping system 5 and the compression stage damping system 6 are arrangedparallel and the lockout device 7 is arranged serially in reference tothat parallel arrangement. This provides the option, simultaneously tolock both the traction stage damping system 5 as well as the compressionstage damping system 6 (lockout), with here too the throttle 12 isprovided as a bypass 11 parallel to the path valve 10, via which oilflow is still allowed to a small extent in order to cause an automaticreturn to a static compression position (SAG).

Finally, FIG. 3 shows a damping arrangement 1 b, which is largelyequivalent to the one shown in FIG. 2, with here the lockout device 7 aonly comprising the path valve 10 and omitting the bypass 11. As soon asthe path valve 10 is closed, the hydraulics circuit 4 is locked and thusalso the traction stage damping system 5 as well as the compressionstage damping system 6. The spring fork provided with this dampingarrangement 1 b is then locked in its present state. However, there isalso the chance to manually compress the spring fork when the path valve10 is opened and in this stronger compressed state the path valve 10 islocked by closing it. In this manner, a simple climbing aid can beadjusted for the bicycle, for example.

FIGS. 4 and 5 show a damping leg 13 of a spring fork, which is providedwith the damping function described in FIG. 1, i.e. a compression stagedamping system that can be locked with a bypass.

The damping leg 13 is provided with a traction stage piston 15 guided ina cylinder 14 and a compression stage piston 16 arranged in a fixedmanner. Above the traction stage piston 15, hydraulic oil 21 isdiscernible, marked by dots, in which the compression stage piston 16 isimmersed.

The compression stage piston 16 has two connecting channels 17penetrating therethrough and it is provided with an adjustment disk 18on its side facing the traction stage piston 15, with said disk beingrotational and provided with a penetrating opening 19 as well as abypass bore 20 arranged off-set in the rotational direction in referencethereto according to the arrangement of the connection channels 17.

The adjustment disk 19 is pressed against the bottom of the compressionstage piston 16 by a pressure spring 22.

In the rotary position of the adjustment disk 18 shown in FIG. 4, thepenetrating opening 19 overlaps a connection channel 17 such that inthis opened position the hydraulic oil can flow unhindered through thepenetrating opening 19 and the connection channel 17 when the springfork is compressed.

In FIG. 5 the compression stage piston 16 is shown in a closed position,with the adjustment disk 18 being in a rotational position in which theconnection channel 17 is covered and thus closed, while the bypass bore20 overlaps another connection channel 17. This way, the compressionstage damping system is blocked except for a defined bypass (provided)by the bypass bore 20. This reduces the rocking motion of the suspensionby movements of the rider, and the fork can lower to the so-called sagposition, i.e. the operational position, which adjusts to approx. 20 to30 percent of the total spring travel when the rider is seated.

When rebounding, i.e. when the traction stage piston 15 is moveddownward, the flow of hydraulic oil lifts the adjustment disk 18 againstthe compression spring 22 off the compression stage piston 16 such thatthe damping lock for the compression stage has no influence on thetraction stage.

In order to rotate the adjustment disk 18, it is connected to a rotaryshaft 23 in a torque-proof manner, yet displaceable in the longitudinaldirection. At the upper end of the cylinder, the compression stagepiston 16 is connected to a fastener 25 via a tube 24 and the rotaryshaft 23 penetrates this tube 24 and is provided at the upper end with arotary knob 26 or a similar rotational handle, via which the adjustmentdisk 18 can be distorted. Snapping means, not shown here, define theopen and the closed positions.

FIGS. 6 and 7 show a practical exemplary embodiment for the dampingarrangement 1 a shown in FIG. 2. Here, both the compression stagedamping system as well as the traction stage damping system can beblocked maintaining the bypass channel.

In addition to the compression stage piston the lockout piston 27 shownin FIGS. 6 and 7 may be provided in a damping arrangement having amobile traction stage piston and a fixed compression stage piston. Forexample, in an arrangement similar to the one shown in FIGS. 4, 5, itcould be arranged slightly above or below the piston exclusivelyembodied as a compression stage piston and connected to the tube 24.Comparable parts in FIGS. 6 and 7 are therefore provided with equivalentreference characters, with this relating to the fastener and also thedrive transmission.

The lockout piston 27 is provided at both sides with washers 28, 28 aimpinging it, rotational in reference to the piston. They are providedwith penetrating openings 19 a located diametrically opposite, which arepositioned in FIG. 6 overlapping the connection channels 17 a in thelockout piston 27. In FIG. 6 the open position of the lockout 27 isshown.

Both washers 28, 28 a are rotated jointly and for this purpose anadjustment part 29 is provided at the interior end of the rotary shaft23, which at the bottom end has a radial flange 30, which carries anentraining pin 31. This entraining pin 31 engages the washers 28, 28 aover the course of their radial extension and the piston 27 within thepartial circumferential slot located within the piston.

The two washers 28, 28 a are impinged towards the piston by pressuresprings 32, with no lifting function of the washers 28, 28 a beingprovided, rather the springs exclusively serve to compress theadjustment disks to the piston.

The upper washer 28 is allocated to a traction stage, thus it serves tocontrol the flow of hydraulic oil during rebound, while the lower washer28 a serves for the flow control in the compression stage, thus duringthe compression of the fork.

The actuator 29 is connected to the rotary shaft 23 embodied as amulti-sided shaft, by which the washers 28, 28 a are rotational into thelockout position (FIG. 7) or the open position (FIG. 6). In the lockoutposition, one connection channel 17 a is completely closed, while theother connection channel 17 a remains passable via bypass bores 20 a inthe washers 28, 28 a. In this lockout position of the washers, both thetraction stage damping system as well as the compression stage dampingsystem are largely blocked, with an automatic adjustment to theso-called sag-level being possible by the bypass formed by the bores 20a.

1. A spring fork, comprising a suspension system and hydraulic damping,with a compression stage damping system (6) for a compression processand a traction stage damping system (5) for rebounding being provided,having at least one piston (3, 16, 27) located in a cylinder (2) withcylinder chambers located on both sides of the piston and at least oneconnection channel (17, 17 a) connecting at least one of the cylinderchambers provided at both sides of the piston for hydraulic medium (21)to flow, with the compression stage damping system (6) activated duringcompression being locked by the connection channel being closed via aclosing device, at least one bypass channel (11, 20, 20 a) with across-section reduced in reference to the connection channel (17, 17 a)being open when the compression stage damping system (6) is closed.
 2. Aspring fork according to claim 1, wherein the connection channel (17, 17a) and the bypass channel (11, 20, 20 a) are arranged in the piston (3,16, 27) and can be alternately opened or closed.
 3. A spring forkaccording to claim 1, wherein a locking element is provided at theconnection channel (17, 17 a) to partially close the connection channel(17, 17 a) to a cross-section equivalent to the at least one bypasschannel (11, 20, 20 a).
 4. A spring fork according to claim 1, whereinboth the compression stage damping system (6) as well as the tractionstage damping system (5) can be blocked and that the at least one bypasschannel (11, 20, 20 a) provided has a cross-section reduced in referenceto throttle or penetrating openings (17, 19).
 5. A spring fork accordingto claim 1, wherein a compression stage piston (16) and a traction stagepiston (15) are provided as the at least one piston, the compressionstage piston (16) is provided with the at least one penetratingconnection channel (17), a side of the compression stage piston facingthe traction stage piston (15) is covered by a washer (18) that isrotational in reference to the piston (16) and spring-loaded in adirection of the compression, which is provided with at least twoopenings (19, 20) having different cross-sections, that can be made tooverlap with the connection channel (17) by rotating the washer (18). 6.A spring fork according to claim 5, wherein the compression stage piston(16) is connected via a tube (24) to a fastener (25) located at an upperend of the cylinder and that a rotational shaft (23) penetrating thetube and the piston (16) is provided with a rotational handle (26) at anexterior end and at an interior end is connected to the washer (18) in atorque-proof manner and is displaceable in a longitudinal direction. 7.A spring fork according to claim 5, wherein in addition to thecompression stage piston, a lockout piston (27) is provided which isprovided with rotational washers (28, 28 a) impinging it at both sidesand rotational in reference to the lockout piston, which by rotating thewashers optionally can be made to overlap the connection channel (17 a)in the lockout piston.
 8. A spring fork according to claim 7, whereinthe lockout piston and a compression stage piston form a functional unitand the lockout piston is integrated in the compression stage piston. 9.A spring fork according to claim 7, wherein to operate the two washers(28, 28 a), a rotational shaft (23) is connected to rotate the washersat an interior end, having an entraining pin (31) connected to the twowashers for rotating them.
 10. A spring fork according to claim 9,wherein the entraining pin (31) penetrates the washers (28, 28 a) in aprogression of a radial extension thereof and the piston (27) within apartial circumferential slot located in the piston.
 11. A spring forkaccording to claim 10, wherein the two washers (28, 28 a) arespring-loaded towards the piston (27).
 12. A spring fork according toclaim 1, wherein an overall cross-section of the at least one bypasschannel (11, 20, 20 a) for resetting the spring fork from a maximumposition into a normal position is sized for a time ranging fromapproximately 1 to approximately 10 seconds.
 13. A spring fork accordingto the preamble of claim 1, wherein a blocking valve (10) is providedserially in reference to a parallel arrangement comprising a compressionstage damping system (6) and a traction stage damping system (5).
 14. Aspring fork according to claim 1, wherein a remote control to adjust thespring fork to the different operational states is provided.
 15. Aspring fork according to claim 5, wherein the compression stage piston(16) is embodied in a fixed manner and the traction stage piston (15) ina mobile one.
 16. A spring fork according to claim 5, wherein thecompression stage piston in arranged in a mobile manner and the tractionstage piston in a fixed one.